No Covers in Carousel when Sideloading

[dkbush]

My dad's kindle fire that I bought him will not load books using a usb as for some reason his computer will not recognize his kindle (my laptop recognized it though). I have a lot of non-Amazon books that I have been trying to send him and figured we could use the email directly to kindle method. It does work but unfortunately, it will not show the book covers on the kindle's carousel (but it shows them on his bookshelf).

I have tried everything to no avail. I am loading the books on Calibre and converting them to .mobi format. I have searched and tried all types of responses, i.e., took out the pdoc when converting; tried both checking and unchecking the share on facebook button, have emailed directly from Calibre and also tried going to the actual book folder and emailing it from there, have selected the option to embed the cover with the book on metadata options. He has rebooted, opened and closed the book, etc. Nothing works. I have found no solution no matter what we try. I understand this to be an Amazon software glitch. Can someone help?

I just cannot seem to find an answer to this problem.

[MikeGolf]

Try adding the ebok tag, resize the covers to 550 by 800, then convert the book to mobi.